textproduct: Quad Cities

KEY MESSAGES

- Heat and humidity returns Sunday and into Monday. Heat indices around or exceeding 100 degrees are becoming increasingly likely Sunday and Monday. A Heat Advisory in northwest Illinois and an Extreme Heat Warning for the rest of the area have been issued for Sunday. An Extreme Heat Watch is in effect for all areas for Monday.

- Thunderstorms are possible (10-40% chance) Sunday night into Monday and may be strong to severe. The SPC has issued a Marginal-to-Slight Risk (Level 1 to 2 out of 5) for severe weather with damaging winds being the primary hazard.

SHORT TERM /THROUGH SUNDAY/

Issued at 251 AM CDT Sat Jul 25 2026

Satellite imagery early this morning shows a thick deck of stratocumulus stretching from Minnesota to southern Illinois. Across parts of eastern Iowa, western Illinois, and northeast Missouri, this low cloud deck will help keep lows slightly warmer this morning in the upper 60s. By mid-day, clouds will lift out as they move east, lingering into the early afternoon in far eastern Iowa and northwest Illinois. This will help limit highs in these areas to the low to mid-80s, with areas to the west reaching the mid- to upper 80s.

Saturday night into Sunday, lows will drop into the low 70s. A feature of particular note in many of the 00Z CAMs is a cluster of showers and storms across parts of western and central Iowa. This cluster is associated with a vort max that rides along the edge of the upper-level ridge. Many CAMs suggest that remnants of this cluster will reach eastern Iowa by Sunday morning and decay shortly afterward. If this were to happen, lingering cloud cover could help temper high temperatures slightly on Sunday, though a hot day with temperatures in the low to mid-90s will still be in store due to a near continuous stream of WAA. Combined with very humid conditions, this will support heat indices in the 100s and potentially exceed 105 degrees (50-90% chance north to south). An Extreme Heat Warning is in effect for eastern Iowa, west- central Illinois, and northeast Missouri and a Heat Advisory is in effect for northwest Illinois on Sunday afternoon.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 251 AM CDT Sat Jul 25 2026

Sunday Night through Monday Night Sunday night, the question turns from heat to storm potential as a shortwave moves through. While decent shear of 25-35 kts and instability will be in place, it is possible that the environment remains capped due to warm temperatures at 850 and 700 mb. Without strong forcing to break this cap, it is possible that no storms occur. Any storms that do develop will be able to take advantage of the shear and instability, with the primary threat being damaging winds. Due to this risk, SPC has a Slight (level 2 of 5) risk for severe thunderstorms for the Highway 20 corridor and a Marginal (level 1 of 5) risk for the remainder of the area.

Heat and humidity are expected with warm lows in the mid-70s Monday morning, which will help temperatures reach into the low to mid-90s and heat indices in the 100s. The primary limiting factor to this would be storms lingering from overnight through Monday morning, though uncertainty in storm initiation and evolution limits the confidence in whether temperatures will be lower. As such, an Extreme Heat Watch remains in effect for the entire area through Monday evening.

Another round of storms is possible Monday afternoon and evening as a cold front pushes through the region. Shear will remain similar to Sunday, though with the greatest shear now being to the east across northeast Illinois. This could help limit the number of storms across our region, as greater shear could allow for the development of an organized cluster of storms to our east.

Tuesday through Friday Following the passage of storms with the cold front overnight into Tuesday, high pressure will build in on the northeast periphery of the upper level ridge. The cold front will help slightly lower heat indices into the mid-90s with the introduction of a drier airmass, though this heat will remain through both Tuesday and Wednesday as we remain under the influence of the ridge.

By midweek, the greatest question is when the ridge retrogrades and brings us back into the summertime storm track and grants us a reprieve from the heat.The majority of the guidance has this change towards the end of the period around Thursday and Friday, though there a few outliers that have it as early as Wednesday. With this return to the storm track, there is the potential for another system to pass through as soon as Friday, though changes in speed could have it arrive earlier.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1200 PM CDT Sat Jul 25 2026

The solid stratus from this morning is gradually easing in coverage and lifting in its cloud bases. Areas of MVFR ceilings will continue through 20Z with high confidence, and then likely fading by 21Z or 22Z.

For tonight, some light haze/BR may developing in the incoming very humid air mass. Otherwise, the possible concern is for isolated storms to move into or develop over eastern Iowa and northwest Illinois after 09Z or so. Confidence in these has inched up a bit, but still on the lower end, with coverage likely to be <25% if they were to develop.

Occasional south-southwest gusts on Sunday afternoon could reach 16-19 kt.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for IAZ040>042-051>054-063>068-076>078-087>089-098-099. Extreme Heat Watch from Sunday evening through Monday evening for IAZ040>042-051>054-063>068-076>078-087>089-098-099. IL...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for ILZ009- 015>018-024>026-034-035. Extreme Heat Watch from Sunday evening through Monday evening for ILZ001-002-007-009-015>018-024>026-034-035. Heat Advisory from 11 AM to 9 PM CDT Sunday for ILZ001-002-007. MO...Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for MOZ009- 010. Extreme Heat Watch from Sunday evening through Monday evening for MOZ009-010.